Prepare hard boiled eggs, cool and peel. You can cook the eggs up to 3 days prior.
Remove beets from the pickled beet jar. Take about 2 cups of beets and sliver thinly, vertically and store in a separate container. Reserve the remainder in a separate container. (You can use more beets to suit your taste)
Submerge the hard boiled eggs and the onion slivers in the liquid, seal the jar and refrigerate for 24 hours. If not ready to assemble the salad remove the eggs from the juice and transfer to a separate container.
Spread greens out on a platter. Remove the onion slivers and eggs from the beet juice. Slice the eggs into thin rounds. Spread onions and eggs and beets evenly around the greens.
Mix the dressing in a jar and shake well. Sprinkle over the salad. Distribute the grated feta evenly over the salad.